A LEADING private school has launched the biggest fundraising drive of its kind to replace its ageing buildings.

St Paul's School in Barnes needs at least £150 million over the next 30 years to overhaul the 1960s prefabricated classrooms, which are nearing the end of their lifespan.

So far the boys' school has secured £45 million towards the crucial first phase, which will cost £70 million, and includes 18 new science labs.

Founded in 1509, St Paul's has the best record for GCSE results in the country and boasts illustrious former pupils including John Milton, Field-Marshal Montgomery, and Shadow Chancellor George Osborne.

St Paul's High Master Martin Stephen said the famous 867-pupil school had launched the fundraising drive to secure its future.

Without the money, the school would have faced "serious problems", he said.

But already, a "staggering" £25 million has been donated towards the first phase of the 30-year project, to add to £20 million of existing resources.

"Amidst all the confusion and uncertainty of recent months people still have a passion for education and a willingness to support our groundbreaking campaign," he said

The school moved to its present site in Barnes in the late 1960s.

Its buildings were constructed using the prefabricated "Clasp" system of the time but were not expected to last for more than 50 years.

The Clasp design was initially rolled out among state schools in the 1960s as part of a government scheme but quickly spread.

The prefabricated buildings could be put up quickly and relatively cheaply, and on land which was unsuitable for more conventional designs.

But four decades later, the buildings at St Paul's are "boiling in summer and freezing in the winter", according to Dr Stephen. They also have a massive carbon footprint, he said.

"We shall be able to replace environmentally unfriendly buildings with superb designs that have the lowest possible carbon footprint," Dr Stephen added.

The school launched the public phase of its fundraising campaign at a black-tie dinner at Mercers' Hall in the City last night.

St Paul's wants to move to a "needs blind" admissions policy within 30 years, where any pupil with the ability to succeed is offered a place, regardless of whether their parents can afford the fees.

New buildings are seen as key to achieving this goal. The original school stood in St Paul's Churchyard but was destroyed along with the Cathedral in the Great Fire of London before a second building was erected on the same site in 1670.

A series of moves saw St Paul's relocate to Berkshire during the war, while the Army – under Montgomery – took over its Hammersmith buildings.In 1968 the school moved to its present site and buildings in Barnes.